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Pre- to post-Cordilleran transposition history of Joss Mountain; insights into the exhumation of the Shuswap Complex, southeastern Canadian Cordillera

Davide Zanoni, Yvette D. Kuiper and Paul F. Williams
Pre- to post-Cordilleran transposition history of Joss Mountain; insights into the exhumation of the Shuswap Complex, southeastern Canadian Cordillera
Lithosphere (September 2014) 6 (6): 419-442

Abstract

We present new multiscale structural, mineral chemical, and U-Pb isotope dilution-thermal ionization mass spectrometry (ID-TIMS) data in order to unravel part of the tectono-metamorphic evolution of the Shuswap complex in the southern Canadian Cordillera. We reconstructed the pressure-temperature-deformation-time (P-T-d-t) history of the Joss Mountain domain within the Shuswap complex. The west-dipping Greenbush shear zone separates the Joss Mountain domain from the structurally lower Thor-Odin culmination to the east, the southern culmination of the Monashee complex, and one of the structurally deepest parts of the Shuswap complex. At Joss Mountain, the protolith of an orthogneiss crystallized at ca. 360 Ma which is is consistent with Late Devonian arc magmatism along the western paleomargin of North America. Joss Mountain metasedimentary rocks and orthogneiss were transposed at approximately 21-29 km depth over a period of at least 20 m.y., and possibly more than 38 m.y., during Late Cretaceous to Paleocene mature stages of Cordilleran continental collision. This mature collision took place while slow detachment of the subducted oceanic lithosphere occurred and thermal conditions were approaching those of a crust undergoing postorogenic thermal relaxation. Transposition at Joss Mountain ended earlier and exhumation started earlier than in the Monashee complex. Exhumation occurred under conditions of near-isothermal decompression and geothermal gradients consistent with lithospheric thinning. Earlier and slower exhumation of the Joss Mountain domain than of the adjacent northwestern Thor-Odin culmination may have resulted from normal movement along the Greenbush shear zone contributing to the exhumation of the Shuswap complex.


ISSN: 1941-8264
EISSN: 1947-4253
Serial Title: Lithosphere
Serial Volume: 6
Serial Issue: 6
Title: Pre- to post-Cordilleran transposition history of Joss Mountain; insights into the exhumation of the Shuswap Complex, southeastern Canadian Cordillera
Affiliation: Universita degli Studi di Milano, Dipartimento di Scienze della Terra A. Desio, Milan, Italy
Pages: 419-442
Published: 20140905
Text Language: English
Publisher: Geological Society of America, Boulder, CO, United States
References: 149
Accession Number: 2014-096959
Categories: Structural geologyIgneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. charts, 4 tables, geol. sketch maps
N50°47'60" - N50°51'00", W118°30'00" - W118°25'00"
Secondary Affiliation: Colorado School of Mines, USA, United StatesUniversity of New Brunswick, CAN, Canada
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201449
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